A definitive evaluation of the predictive and prognostic usefulness of specific tumor markers has been hindered by the lack of an adequate number of patients for achieving statistically valid endpoints. Even though systems for collecting archival breast cancer tissue blocks have existed for many years in local, state or national institutions, these resources have shown limited usefulness due to several reasons, such as: 1 - lack of sufficient number of cases for a specific disease, 2 - lack of adequate followup or patient information, 3 - variability in therapeutic modalities, 4 - poor computerization systems to retrieve the desired cases, and 5 - insufficiency of funds and personnel for organizing the archival material and data bank for breast cancer patients. Therefore, what is needed is a breast cancer registry that would provide: 1 - archival breast tissue in sufficient amounts to allow researchers to draw valid statistical conclusions, 2 - information on the stage of the disease, treatment modality and followup, 3 -have adequate histological diagnosis, lymph node status, tumor grading, and other demographic data such as patient age, menopausal status, ethnicity, and social conditions, and 4 - have enough breast cancer cases across large segments of populations of specific ethnic properties. For this purpose we propose to organize the Fox Chase Cancer Center breast cancer registry based on the infrastructure of our cancer center and the Fox Chase Network, Inc. The goals of the proposed Breast Cancer Registry are: 1. To provide archival breast tissue (paraffin blocks) of 7,805 breast cancer cases, for the study and validation of tumor markers for breast cancer prognosis. 2. To provide information on tumor characteristics (primary site, laterality, tumor size, histological type, tumor grade, estrogen and progesterone receptors, content, lymph node status and a general summary stage for each case available in the registry. 3. To provide information on a: patient characteristics (sex, age/date of birth, race/ethnicity, menopausal status, income level according to zip code of residence, admission date and discharge date); b: information on first course treatment (surgery, radiation therapy, chemotherapy, hormone therapy, biologic response modifiers, and other); and c: to provide years of followup (last contact date for survival calculation, vital status and tumor status) for each case available in the registry. 4. To organize the means for making known to researchers and the scientific community of the availability of the Fox Chase Breast Cancer Registry. 5. To assure that the material of the registry reaches the researchers in an expeditious manner and to maintain adequate quality control of the archival tissue and of the data bank file of each case. 6. To establish guidelines for an interactive cooperation with other Breast Cancer Registries. 7. To establish guidelines for the cooperative functions of the Research Evaluation and Research Panel (REDP) who will identify high priority research studies. 8. To provide guidelines for the activities and role of the Coordinating Committee of the Registry. The ultimate rationale of the breast cancer registry is to use the infrastructure described above to provide archival breast tissue paraffin blocks (and optionally, frozen tissue and blood samples) from breast cancer patients with their adequate demographic and clinical data to researchers who request this material for validation of prognostic indicators in Breast Cancer.